Preheat oven to 375 degrees. Line a baking sheet with parchment paper. This isn't a must-do, but it really helps with cleanup.
On your surface, lay out one sheet of filo dough. These are fragile, so be careful. Brush it lightly with olive oil. The sheet doesn't need to be soaked, just a light brushing.
Add another sheet on top and again, brush lightly with olive oil. Place your salmon filet in the middle of one of your short ends, as shown in the photos.
Brush the filet with olive oil, sprinkle with salt and pepper. Then add about 1 tablespoon of feta and about 1 tablespoon oregano. Then top this with about ¼ cup spinach.
Fold in the sides on the filo, it might break a little, so don't stress. Then gently roll the salmon over and over until it is wrapped in a parcel. Check the photos for descriptions. Sorry, for some reason this is really hard to write out. Brush the top with olive oil as well.
Repeat the process with the remaining 3 salmon filets. Place on the prepared baking sheet and into the oven.
These will need to bake for 18-25 minutes. They should be a beautiful golden brown. This will actually steam the salmon as it bakes, creating the perfect salmon texture!
Remove from oven. They are best served right away while they are still warm!
If you want to use these for meal prep, allow them to cool to room temperature, then store them in the fridge for up to 3 days in an airtight container. Just know that They will not be crispy when you reheat but are still delicious.
Now, sit back and enjoy. You deserve it.